I did the same thing, for the same reason. Thought they were too dim. Bottom line, if you are using the correct bulbs and the proper amperage is getting to them, then thats the way they were meant to be. I suppose you could try some brighter rated bulbs, but the next step up might make them too bright, and take away from how they are supposed to look (and cause other problems).
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?